(1) Field of the Invention
The present invention relates to feed control devices, and more particularly to an improvement in feed control devices of the type which are designed to effect the regulation of the flow of balls to a ball grinding machine. More specifically, this invention consists of a technique for controlling a fluidic ball feed mechanism to prevent spillage of balls at the entrance to a ball grinding station. Accordingly, the general objects of the invention are to provide novel and improved apparatus and methods of such character.
(2) Description of the Prior Art
It has long been a common practice in the prior art to perform a machining operation on ball bearings for purposes of reducing them to the desired size and sphericity. Moreover, the particular machining operation which is most often utilized in this connection involves some form of grinding operation. To this end, the balls are made to pass through a ball grinding machine. However, in actual practice, in order to ensure that the balls are ground properly, it has been found most desirable to effect the necessary grinding of the balls by causing them to make a number of passes through the ball grinding machine. During each of theses successive passes, the balls are further reduced until finally, when the balls leave the ball grinding machine for the last time, they each embody the size and sphericity desired of them.
The original models of ball grinding machines embodied a mode of operation which commonly was characterized as being in the nature of a discontinuous form of operation. Namely, in accordance therewith, a predetermined quantity of balls had to be manually loaded into the ball grinding machine, whereupon the balls were ground. Once the balls had been ground to the desired extent, the balls then had to be manually removed from the ball grinding machine. Thereafter, a new group of balls would be loaded into the ball grinding machine, followed by the steps of grinding and removing the balls from the ball grinding machine. This necessity of having to repeatedly load and unload balls in groups adversely affected the production rate at which balls could be ground in the early models of ball grinding machines, and thus represented a serious disadvantage which such machines possessed.
One of the first improvements which was sought to be made in the early models of ball grinding machines involved the attempt to provide the latter with means operable to permit the balls to be fed continuously to the grinding machine. Many continuous feed approaches have been pursued. One early version of a continuous ball feed system is to be found described and illustrated in U.S. Pat. No. 1,772,365 to Pratt. With the advent of continuous ball feeding systems, not only was there achieved an increase in the production rate at which balls could be ground, but the need for each ball grinding machine to be manned by a separate operator was eliminated. Rather, the use of a continuous ball feeding system made it feasible for one employee to monitor the operation of a plurality of ball grinding machines, thereby concomitantly effecting a reduction in the cost of labor required to perform the desired machining of balls through the use of ball grinding machines.
However, with the coming of ball grinding machines equipped with continuous ball feeding systems, it soon became apparent that there existed a need to be able to regulate the rate at which balls were being fed to the ball grinding machines. To this end, a variety of schemes were devised whereby the flow of balls to a ball grinding machine could be regulated so as to compensate for the existence of variations in such characteristics as the nature, size, weight, etc. which might prevail between the different types of balls which were to undergo grinding in a ball grinding machine. Commonly, the methods employed to effect such regulation of the feeding of balls to a ball grinding machine involved the making of adjustments to the ball grinding machine and/or the ball feeding system prior to the commencement of the grinding operation. Once the grinding operation had been commenced, very little further regulation of the flow of balls to the ball grinding machine could be accomplished.
In recent years, a number of additional refinements have been made to the construction as well as the mode of operation of ball grinding machines. One such refinement involved the equipping of ball grinding machines with means operable to effect the automatic regulation of the ball feed while the ball grinding machine was running. Such automatic regulators often had the capability of completely shutting down the operation of the conveyor system, by means of which balls were fed to the ball grinding machine, in the event that some predetermined operating condition was indicated as being present. One form of automatic shut-off which has been employed comprises a feeler arm connected in an electrical detection circuit whereby, when abnormal ball feeding conditions are sensed to exist, appropriate corrective action can be initiated in response to a signal being generated by the feeler arm. Such a system is to be fond described and illustrated in U.S. Pat. No. 3,250,042 to Messerschmidt.
Notwithstanding the many improvements which have been made to date to ball grinding machines and the ball feeding mechanisms commonly found associated therewith, there has nevertheless been found that a need has existed to provide a ball feed control system which would be less complex in construction and less costly to provide than the mechanisms currently available, but yet one which would still be capable of providing the desired degree of dependable operation.